1. Field of the Invention
The present invention relates to network protectors and, more specifically, to an external operating handle that may be used by an operator wearing thick gloves.
2. Background Information
Secondary power distribution networks consist of interlaced grids which are supplied by two or more sources of power so that the loss of a single source of power will not result in an interruption of service. Such networks provide the highest level of reliability possible with conventional power distribution and are normally used to supply high-density load areas such as a section of a city, a large building, or an industrial site. Between the power sources and the network is a transformer and a network protector. The network protector consists of a circuit breaker and a control relay. The circuit breaker includes at least one set of main contacts that move between an open position and a closed position. When the main contacts are closed, electricity may flow through the network protector. The contacts are coupled to an operating mechanism structured to move the contacts between the first and second positions. The operating mechanism may be actuated by a trip device structured to sense an over-current condition or by a mechanical trip assembly that is manually operated. The control relay senses the transformer and network voltages and line currents and executes algorithms to initiate breaker tripping or closing action. Trip determination is based on detecting an overcurrent condition or reverse power flow, that is, power flow from the network to the energy source.
Network protectors are often found in dust-proof or moisture-proof housings, or vaults, which are disposed in subterranean passageways in large metropolitan areas. Given their urban, subterranean location, increasing the size of the vault to accommodate larger network protectors is costly and difficult. As such, it is more efficient to reduce the space occupied by certain network protector components so as to allow space for other newer/larger components. That is, by reducing the size of one component or sub-component, another component may be added or an existing component's size may be increased.
The network protector components, the circuit breaker, the relay and other associated devices, are located within a housing assembly within the vault. For safety, the circuit breaker should be tripped before the circuit breaker can be removed from the enclosure. To accomplish this, network protectors include a mechanical trip assembly which is structured to interact with a trip bar coupled to the operating mechanism. The trip bar is structured to move between a first position and a second position. In the first position, the trip bar prevents the main contacts of the network protector circuit breaker from moving into the closed position. Thus, when the trip bar is in the first position, the contacts are open. In the second position, the trip bar allows the main contacts to be moved into the closed position. The trip bar could also be moved into a reset position corresponding to a reset position for the circuit breaker.
To safely remove, or install, the circuit breaker from the enclosure, the main contacts must be in the first, open position. To trip the circuit breaker, the trip bar was moved into the first position by the mechanical trip assembly. The mechanical trip assembly included an external handle coupled to a shaft that extended from outside the housing assembly to within the housing assembly and a coupling device that extended between the shaft and the trip bar. Typically, the shaft extended laterally within the network protector housing and extended beyond either the left or right housing sidewall. The handle was coupled to the shaft and extended radially, that is, perpendicular to the axis of the shaft. As such the handle extended generally parallel to the plane of the housing sidewall. If there was sufficient space within the vault, the handle may also have a perpendicular rod, or grip, extending laterally. When the shaft was rotated, the coupling device moved thereby actuating the trip bar. A typical mechanical trip assembly is structured to be actuated prior to opening the door to the enclosure.
Accordingly, the mechanical trip device included an external handle that could be actuated prior to opening the door to the housing assembly. Actuating the external operating handle moved the mechanical trip assembly, and therefore the trip bar, into the first position. Thus, before the housing assembly is opened, the circuit breaker was tripped. If required, however, it was possible to open the housing assembly with the trip bar in the second position, leaving the circuit breaker in the closed position. After maintenance and/or repairs are performed on the circuit breaker or the relay, and after the circuit breaker is installed in the vault, the mechanical trip assembly, and therefore the trip bar, is moved, if required, into the reset position, and then into the second position so that the main contacts could again be closed.
To prevent the accidental actuation of the external handle, the typical handle included a locking device. The locking device included a guide plate fixed to the outer side of, and extending generally parallel to, the housing assembly sidewall, and a pin. The guide plate and the handle are disposed adjacent to each other and included openings sized to allow the pin to pass therethrough. The openings on the guide plate were positioned to align with the handle opening when the handle was in either the first or second position. Thus, the handle, and therefore the mechanical trip assembly, could be locked in either the first or second position by inserting the pin through the handle and into the guide plate. The locking pin was actuated, for example, by a push lever. That is a lever actuated by a user was structured to move the pin between the locked and unlocked positions.
The disadvantage to the prior art handle locking devices is that the actuating means for locking and unlocking the handle were relatively small. That is, formerly, users were not required to utilize safety gloves, or the gloves that were required were not as bulky, and other protective measures when actuating the handle. Thus, the release mechanism for the handle assembly was sized for an ungloved hand. Today, users utilize thicker protective clothing that makes gripping the former type of release device difficult. Additionally, the prior art locking devices were often difficult to access due to the confined nature of the vault. These confined spaces are prone to cause damage to the newer, thicker protective clothing as a user may catch and tear the clothing.
There is, therefore, a need for an external handle that is easy to grip by a user wearing thick gloves.
There is a further need for a handle locking device that is easy to access by a user wearing thick gloves.